1. Field of Invention
The present invention relates generally to the field of devices for deburring and cleaning metallic structures. More particularly, the present invention relates to a device for providing surface preparation for metallic structures such as piping and tubing. More particular yet, the present invention involves an attachment for a rotary power tool, where the attachment is a rotary abrasion device that cleans the outside of the end of a pipe or tube in preparation for soldering or welding procedures. As well, the rotary abrasion device can be utilized for inner-surface preparation--e.g., reaming and cleaning the inside of the same end of piping and tubing.
2. Description of Prior-art
While the general field of metalworking with piping and tubing involves problems associated with removal of oxide build-up and surface irregularities (e.g., burrs, nicks, cuts), the more specific field of pipefitting will be discussed. It should be noted that this discussion is limited to the specific field of pipefitting for the sole purpose of illustrative clarity and is not meant to limit the intended scope of the invention.
In the field of pipefitting, the general operation for soldering pipes together begins with the process of cutting a pipe to length. Typically, pipe cutters are used. These cutters are well known in the art and are generally C-shaped and include a cutting wheel at one end and bearings at the other end. The pipe is positioned within the cutter between the cutter's ends and tightened so that the cutting wheel and the bearings come into contact with the outer surface of the pipe. The cutter is then rotated around the pipe while the cutter is increasingly tightened. The cutting wheel cuts deeper into the piping with each turn of the cutter. This process continues until the piping is eventually cut through where the cutting wheel made contact. This common cutting process yields at least two undesirable effects.
Cutting pipes in the field of pipefitting creates undesirable metal burrs along the inner surface at the cut edge of the pipe, and slightly decreases the diameter of the pipe at the cut edge. Any such irregularities in the pipe can affect the flow of whatever fluid (e.g., refrigerants, water, . . . etc.) is used within the finished system (e.g., HVAC, hot water heater plumbing, heat pump system, . . . etc.). Additionally, metal burrs that are not removed can break off and foul any machinery and apparatus (e.g., pumps, sensors, heating elements, . . . etc.) that are incorporated into the finished system. In addition to the problems related to the piping's inner surfaces, exposed surfaces of metallic piping are often subject to oxidation. This is particularly acute with respect to copper piping where the oxides that naturally form on the pipe's outer surface must be removed to enable a secure fit and weld. It is common that using a pipe cutter also reduces the diameter of the pipe at the very end and may leave excess material (i.e., burrs) on the edges of the cut. If not properly removed, any subsequent weld will be weak and subject to increased chance of leakage. Further, excess material such as copper filings and burrs within a domestic hot water heating system can encourage undesirable calcifications within the pipes requiring costly repair or replacement of pipes.
In operation after the pipe has been cut to length, a pipefitter will typically use a manual reamer to cut away burrs from the cut edge and to widen the mouth of the pipe opening back to its original diameter. This includes preparation of the inner surface of the piece having the wider diameter as well as the outer surface of the piece to be soldered or brazed thereon. The preparation of the surfaces typically involves abrading the surfaces to be joined with an abrasive means. Conventionally, this is accomplished manually using either sandpaper of a suitable rugosity for metal or hand-held wire bristles. Such manual brushes are typically worn and misshapen beyond repair after extended use and then become unwanted trash. After the outer and inner surfaces near the cut edge of the pipe are manually provided with an oxide-free, shiny appearance, the pipefitter applies flux or a similar solder-drawing compound onto the cleaned portions of tubing to be soldered and pushes one into the other. Heat is then applied and followed by solder. The workpiece is cooled so as to allow the drawn-in solder to harden and form a fluid tight joint.
From the operation described above, it becomes critically apparent that proper surface preparation occurs prior to the soldering or brazing. This includes the requirements that the cut end of the pipe be restored to its full diameter, the exposed surfaces be free from any oxidation, and that any excess material or burrs along the cut must be removed. In the past, the widening has been accomplished by the separate step of reaming the cut end on its inner surface with a reaming tool while the removal of any burrs and oxidation was accomplished via sandpaper or some wire bristles. Among the prior-art references, several known devices typify the aforementioned pipe preparation tools and some attempt to alleviate the problems associated with manual reaming and deburring. However, none of these below patents touch the disclosure of this invention as described herein.
The device of U.S. Pat. No. 5,168,660 issued to Smith is an attachment for an existing drill that includes two or three brushes. The brushes are spring-biased to press against a pipe upon insertion. However, this device is entirely lacking any pipe guides or brush-limiting mechanisms that would prevent excessive wear of the brushes if the pipe were twisted off its ideal axial placement.
The device of U.S. Pat. No. 4,862,549 issued to Criswell et al. is an attachment for an existing drill consisting of an internal brush for cleaning of fittings and an external brush for cleaning of tubes prior to soldering that are provided in a single attachment that may be driven by either a manual or motor driven means. However, the device of Criswell et al. fails to provide any structure to maintain a pipe's end aligned while limiting deformation and wearing.
The device of U.S. Pat. No. 4,467,489 issued to Begneaud is a complex drill attachment that includes a brush device that is either manually operated or motor driven for cleaning the threads of bolts and studs and threaded pipe ends using combinations of bristles and solvent or air application.
The device of U.S. Pat. No. 4,014,062 issued to Scott et al. is a pipe-cleaning device that includes three rotating brushes and requires an Allen wrench to move each brush. As well, no inner cylindrical guide is present to align the pipe and prevent excessive wear of the brushes.
The device of U.S. Pat. No. 3,820,184 issued to Stone is a whole-pipe-cleaning device that includes multiple rotating brushes. There is no inner cylinder that would guide the pipe and maintain its alignment during use. This would lead to excessive brush wear and subsequent brush failure.
The device of U.S. Pat. No. 3,188,674 issued to Hobbs is a rotary tube end cleaner which is essentially a socket or cylindrical housing having a cylindrical inner surface lined with an abrasive material such as wire bristles, sandpaper and the like. The socket can be mounted to an electric drill and is provided with adjustment screws for changing the distance between the oppositely facing abrasive surfaces, thereby permitting adjustment for varying diameters of piping.
The device of U.S. Pat. No. 2,866,212 issued to White et al. is a pipe-cleaning device that includes a mechanism for cleaning both the inner and outer pipe surfaces. A significant problem with the design of this device is that any cleaning of the outer pipe surface may not be uniform. Indeed, the pipe is likely to be brushed in such a way that longitudinal ruts jeopardize the pipe thickness.
The device of U.S. Pat. No. 2,635,393 issued to Barth is a pipe-cleaning device that includes centrifugally-actuated brushes. This device fails to provide any limit for brush actuation against the pipe surface other than the brush itself such that this design will result in fast wearing brushes. While a boss element is shown that attempts to align the given pipe, the boss element fails to support the entire inserted length of the pipe and does not prevent twisting of the pipe during use. Thus, pipe thickness will be subject to uneven wear and gouging.
None of the patents discussed above adequately provides for accurately reaming the end of a cut pipe to remove all excess material (i.e., deburring) while also abrasively cleaning the surface to be welded. Common to many of the prior-art devices, reaming and deburring is a prerequisite operation. That is to say, reaming and deburring is performed prior to the application of the prior-art devices for abrasively cleaning the pipe surfaces that are to be welded. None of the prior-art devices teach or render obvious the rotary abrasion device of the present invention wherein the insertion of a pipe end into a single tool and operation thereof accurately and efficiently accomplishes reaming of the cut end of the pipe, removal of any excess material, and abrasive cleaning of the welding surfaces.
Contemporary improvements in these prior-art devices have been limited to a cumbersome design that fails to produce uniform and efficient surface preparation of pipes. The prior-art devices do not provide any compensation for unwanted twisting of the pipe within the given cleaning device. This will directly result in undesirable deformation of the abrasive means (e.g., brushes) and ultimately requires early replacement of the worn brushes. As the prior-art fails to maintain a pipe's end in a centered position during cleaning, the uneven and excessive wearing of the brushes requires frequent replacement that is both costly and time consuming. Further, this inability of the prior-art to adequately secure the pipe's end creates a significant problem in that any cleaning of the welding surface may not be uniform. Indeed, the pipe is likely to be brushed in such a way that non-uniform marks and ruts jeopardize the pipe thickness
Accordingly, it is desirable to provide for a new and improved, effective rotary abrasion device for providing proper surface preparation suitable for metal-working purposes such as, but not limited to, copper piping installation. What is needed is such a rotary abrasion device that is easily operated. What is also needed is such a rotary abrasion device that can utilize old, worn, and normally-discarded manual brushes. What is further needed is such a rotary abrasion device that does not require specialized actuation means, but instead can be used in any hand-held power tool (e.g., drills, cordless screwdrivers, multipurpose rotary devices, and the like). Still, what is needed is such a rotary abrasion device that keeps a pipe's end stabilized and aligned within the device thereby preventing any non-uniform pipe marks or ruts that would jeopardize the wall thickness of the pipe. What is also needed is such a rotary abrasion device that includes an inner cylindrical guide that efficiently operates to both maintain the pipe's end therewithin in stable alignment and automatically limits brush abrasiveness. Still further, what is needed is such a rotary abrasion device that provides an automatic brush adjustment feature which requires few mechanical parts. Yet still further, what is needed is such a rotary abrasion device which overcomes at least some of the disadvantages of the prior-art while providing new and useful self-aligning and brush-wear-limiting features.